Stimulating bone growth and controlling spinal cord pain

ABSTRACT

Bone growth for fusion promotion is stimulated in a mammalian patient in need thereof. Bone growth stimulation is achieved by implanting an electro-conductive bone growth stimulating implant in a region in the patient where bone growth is desired. An external device is worn by the patient to produce a direct current in the implant whereby bone growth is stimulated. The external device produces a magnetic field that induces an electric current in the implant. The electric current stimulates bone growth. The implant contains strips of a biocompatible conductive metal, such as, for example, nickel, gold or titanium. The strips can also be made of a conductive polymer such as for example, graphene. Implants to treat spinal cord pain are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Application No. 61/743,683, filed on Sep. 10, 2012, thedisclosure of which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to methods stimulating bone growth,methods of controlling pain and implants and devices to conduct saidmethods. In particular, implants containing electro-conductive stripsare implanted in a mammalian patient in regions of the body to promotebone growth. An external device is used to produce an electric currentalong the electro-conductive material wherein the electric currentpromotes bone growth along the path of the current. Additionally,implants containing electro-conductive strips are implanted in amammalian patient in regions adjacent to the spinal cord for paincontrol. An external device is used to produce an electric current alongthe electro-conductive strips wherein the electric current promotes painrelief.

BACKGROUND OF THE INVENTION

It is estimated that about six million bone fractures, including about600,000 non-union cases, occur annually in the United States, amongwhich approximately 10% do not heal. In the orthopedic proceduresconducted, about one million performed annually require allograft orautograft. One solution to enhancement of bone healing is through tissueengineering, in which cells, such as osteoblast, fibroblast,chondroblasts, are treated with bioactive signaling molecules, e.g.,insulin or insulin mimetics or scaffolds such as β-TCP (tricalciumphosphate) and collagen under an appropriate environment. Currentmethods of treatment of bone fractures include (a) electro-stimulationdevices (such as PEMF, Exogen and (b) biologics, such as bonemorphogenic proteins (BMPs), e.g., rhBMP-2/ACS (INFUSE™ Bone Graft). Thelatter has been approved by FDA as an autograft replacement in spinefusion (ALIF) with specific interbody cages (2002), as an adjuvant forrepair of tibia fractures with IM nail (2004), and for craniofacialmaxillary surgery (2006), but this method is expensive, costing about$5,000 per application. (Lieberman, J. R., et al., J. Bone Joint Surg.Am., 2002, 84: 1032-1044; Trippel, S. B., et al., J. Bone Joint Surg.Am., 1996, 78: 1272-86.)

Fracture healing is a complex process that involves the sequentialrecruitment of cells and the specific temporal expression of factorsessential for bone repair. The fracture healing process begins with theinitial formation of a blood clot at the fracture site. Platelets andinflammatory cells within the clot release several factors that areimportant for chemotaxis, proliferation, angiogenesis anddifferentiation of mesenchymal cells into osteoblasts or chondroblasts.

The fracture healing process subsequent to the initial hematomaformation can be classified as primary or secondary fracture healing.Primary fracture healing occurs in the presence of rigid internalfixation with little to no interfragmentary strain resulting in directbone formation across the fracture gap. Secondary fracture healingoccurs in response to interfragmentary strain due to an absence offixation or non-rigid fixation resulting in bone formation throughintramembranous and endochondral ossification characterized by responsesfrom the periosteum and external soft tissue.

Intramembranous bone formation originates in the periosteum. Osteoblastslocated within this area produce bone matrix and synthesize growthfactors, which recruit additional cells to the site. Soon after theinitiation of intramembranous ossification, the granulation tissuedirectly adjacent to the fracture site is replaced by cartilage leadingto endochondral bone formation. The cartilage temporarily bridging thefracture gap is produced by differentiation of mesenchymal cells intochondrocytes. The cartilaginous callus begins with proliferativechondrocytes and eventually becomes dominated by hypertrophicchondrocytes. Hypertrophic chondrocytes initiate angiogenesis and theresulting vasculature provides a conduit for the recruitment ofosteoblastic progenitors as well as chondroclasts and osteoclasts toresorb the calcified tissue. The osteoblastic progenitors differentiateinto osteoblasts and produce woven bone, thereby forming a unitedfracture. The final stages of fracture healing are characterized byremodeling of woven bone to form a structure, which resembles theoriginal tissue and has the mechanical integrity of unfractured bone.

The processes of bone metabolism vary from bone repair. Bone metabolismis the interplay between bone formation and bone resorption. Bonerepair, as described above, is a complex process that involves thesequential recruitment and the differentiation of mesenchymal cellstowards the appropriate osteoblastic/chondrogenic lineage to repair thefracture/defect site.

Fractures, or broken bones, are common injuries that can take months oreven years to fully heal. The healing process is generally the same forall fractures. Through a series of stages, new bone forms and fills inthe fractured area. The rate of healing and the ability to remodel afractured bone vary tremendously for each person and, in general, dependon several factors, such as age, overall state of health, the type offracture, and the bone involved. Specifically, smoking, diabetes,obesity, and advanced age can increase the difficulty of fracturehealing due in part to diminished circulation, and other factors notwell understood. Complications of orthopedic surgery and trauma includenon-union or poor union of fractures at fusion sites. Despiteimprovement in fusion-promoting devices and chemicals, accelerated andcomplete healing and fusion between bone surfaces remains at timeselusive.

The use of electrical stimulation to improve the effectiveness offracture healing has grown significantly in recent years. Electrical orultrasound stimulation is a good option for patients who have bonehealing problems, or fractures that have poor healing potential. As thenumber of scientific and clinical studies validating the use ofelectrical or ultrasound stimulation to enhance spine fusion hasincreased, there is a better understanding among spine surgeons abouthow and when to use specific electrical stimulation devices to aid inthe healing of spine fusion. Some of the problems associated with thistype of treatment include patient compliance and accuracy in theplacement of the simulator. Typical treatment regimens include applyingthe bone growth stimulator to the fracture for about 20 minutes to up to4 hours per day in order to provide a benefit. In addition, theplacement of the stimulators must be such that the bone is sufficientlystimulated. Despite the improved understanding of micro-vibration andmicro-electric potentials generated in situ by bone to promote bonehealing during standard or typical stress (Wolff's law), it is stillunclear how one may harness and augment the endogenous bioelectricpotentials to promote further bone growth. Implantable electric bonegrowth stimulators require an additional surgery for removal of thedevice which is always a downside especially for the elderly.

In patients with bone trauma and/or advanced spinal degeneration fusionremains the goal. Two bone surfaces are required to form a healingcallous of bone that connects the two in order to strengthen a fractureor an abnormal motion segment such as seen in spondylolisthesis of thespine. Instrumentation, such as, pedicle screws and rods, andbiochemical technology, such as, bone morphogenic proteins, have beenutilized to attempt this fusion. The shortcomings of these technologiesare potentially extreme. Bone morphogenic protein is alleged to producecancer and male sterility and has shown to produce cyst-like abnormalbone growth and soft tissue swelling. Zara, et al, Tissue Eng. Part A.2011, May, 17 (9-10): 1389-1399. Pedicle screws are notoriouslyassociated with non-union or pseudoarthrosis rates. With the agingpopulation operations to fix broken bones and non-healing callouses inpatients with osteoporosis is a growing problem. The ability ofpiezoelectric pulses, ultrasound, direct currents and inductive couplinghave shown promise in forming new bone in turkey and rabbit models aswell as in humans. Certain braces create an electromagnetic field aroundthe wearer in order to promote inductive coupling, ie, generate acurrent in situ, with questionable results.

There is currently no orthopedic implant that (a) augments an externalelectromagnetic field internally into a direct current and (b) attemptsto use conductive properties of an internal metal alloy and chemicals toinduce a current from one bone surface to another during mechanicalstress. The present invention provides both of these concepts to improvefusion healing in non-union bone fractures. The present invention isespecially useful in promoting osteogenesis in high risk patients, suchas, smokers, diabetics, the elderly, patients with osteoporosis to namea few.

SUMMARY OF THE INVENTION

Briefly, in accordance with the present invention, bone growth forfusion promotion is stimulated in a mammalian patient in need thereof.Bone growth stimulation is achieved by implanting an electro-conductivebone growth stimulating implant in a region in the patient where bonegrowth is desired. An external device is worn by the patient to producea direct current in the implant whereby bone growth is stimulated. Theexternal device produces a magnetic field that induces an electriccurrent in the implant. The electric current stimulates bone growth.Bone growth can be stimulated in any mammal, including but not limitedto, a human, a dog, a cat, an agricultural mammal or a horse. Theimplant contains strips of a biocompatible conductive metal, such as,for example, nickel, gold or titanium. The strips can also be made of abiocompatible conductive polymer such as, for example, graphene.

Additionally, the present invention relates to managing pain or painreduction in patients with spinal cord pain. Pain relief is achieved byimplanting an electro-conductive implant in a region adjacent to thespinal cord where pain relief is needed. An external device is worn bythe patient to produce a direct current in the implant whereby pain isreduced. The external device produces a magnetic field that induces anelectric current in the implant. The electric current acts as a spinalcord stimulator to manage pain. Pain relief can be stimulated in anymammal including, but not limited to, a human, a dog, a cat, anagricultural mammal or a horse. The implant contains strips of abiocompatible conductive metal, such as, for example, nickel, gold ortitanium. The strips can also be made of a biocompatible conductivepolymer, such as, for example, graphene.

Of particular interest in practicing the present invention, abiomechanical spacer or cage is lined with strips of gold or otherbiocompatible conductive metal or polymer. The gold is positioned fromtop to bottom of the spacer and, when activated by a magnetic field,will produce a direct electric current from one side of a fractured boneto the other side of the fracture thereby stimulating bone growth acrossthe fractured zone and thereby reducing the incidence of non-unionhealing. The direct electric current is created by the patient wearingan external device, such as, for example, a brace, a belt, a corset, astrap or a band that produces an electric field adjacent to or aroundthe site of the implant. The electric field interacts with the goldstrips to produce a current that promotes bone growth.

The present invention provides implants and methods that result inimproved healing of fractured bones and promotes fusion of bonefractures. Because the present implants do not contain batteries,surgical removal of the implant is unnecessary. Additionally, patientsat a high risk for non-union healing have an improved recovery and ahigher success rate for complete bone fusion.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A and 1B show a biomechanical spacer that contains biocompatibleelectro-conductive strips.

FIG. 2 shows a representation of a broken bone treated with a bonestimulating implant.

DETAILED DESCRIPTION OF THE INVENTION

When used herein the following terms have definitions described below:

The term “mammal” when used herein includes any mammal especiallyhumans. Non-human mammals include non-human primates, zoo animals,performance mammals, such as, race horse and breeding animals, andcompanion animals such as dogs and cats.

The term “strip(s)” when used herein refers to an electro-conductivematerial; “material” means strands, filaments, elongated pieces of foiland wires of electro-conductive material including any narrow elongatedconfiguration of said material(s).

In practicing the present invention, bone growth for fusion promotion isstimulated in a mammalian patient. The bone fusion treats a bonefracture, which includes bone degeneration from osteoporosis such as isneeded in a spinal fusion. Bone growth stimulation is achieved byimplanting an electro-conductive bone growth stimulating implant in aregion in the patient where bone growth is desired. Preferably, theimplant contains strips of electro-conductive materials (conductivemetals, conductive polymers) that are positioned along the length of theimplant. The implant can be placed between the bone surfaces to befused, onto, or near, hardware (biomechanical spacers (cages), screwsand rods) or in the region where bone growth is desired. Once anelectro-conductive bone growth stimulating implant is in place, anexternal device is worn by the patient to produce a direct current inthe implant whereby bone growth is stimulated. The direction of bonecell growth and migration will follow the direction of theelectro-conductive material in the implant. An external device is wornby the patient around the area of the implant to produce a magneticfield that induces an electric current in the implant'selectro-conductive strips. The electric current stimulates bone growth.Bone growth can be stimulated in any mammal, including, but not limitedto, a human, a dog, a cat, an agricultural mammal or a horse.

The implant contains strips of a biocompatible electro-conductive metal,such as, for example, nickel, gold, a suitable metal alloy or titanium.The strips can also be made of a conductive polymer, such as, forexample, graphene. The exact shape and size of the strips are notcritical to the practice of the present invention. The strips can befoil strips or small diameter wire or filaments. The strips arepreferably arranged in the implant so as to linearly connect a firstbone surface with a second bone surface where the two surfaces aredesired to be fused to heal a bone fracture or fuse spinal vertebrae.Strips are usually about 0.1 mm to about 10 mm in diameter andpreferably from about 1-2 mm. When foil metallic conductors are used thefoil can be 0.1 mm to about 1.0 mm thick and have a width of from about0.1 mm to about 10 mm. Preferably the gold foil is about 0.127 mm thickand from 1-2 mm in width.

The implant of the present invention contains a biocompatible substratewherein the electro-conductive materials or strips are affixed to, orembedded in, the substrate. Suitable substrates include hardware such asbiomechanical spacers (cages), screws and rods. Substrates also includeosteoconductive scaffolding materials that promote bone growth such asautografts, allografts and synthetic osteoconductive scaffolds such ashypoxyapetite and β-tricalcium phosphate. The substrates can optionallycontain piezoelectric crystals.

The present implants can be pre-made by manufacturers who supplysurgical hardware and osteoconductive scaffolding materials byincorporating biocompatible electro-conductive strips into theirproducts as described herein, ie, by making sure that the strips run ina direction across the fracture in order to promote complete bone fusionand reduce the chance of non-union healing. Alternatively, the presentimplants can be in the surgical suite as a patient is being operated onfor a bone fracture or spinal fusion. The electro-conductive materialsare added to a substrate in the surgery suite as a bone fracture surgeryor spinal surgery is being conducted. For example, the surgery team canline the hollow portion of a spacer with gold filaments and then add anosteoconductive scaffolding material into the hollow portion which canadditionally hold the strips in place.

Any biocompatible material can be used to form all or part of a spacerthat will serve as the substrate of the present implant. Suitablematerials include, titanium, stainless steel and/or other surgical grademetals and metal alloys. In addition, various polymers, such aspolyetheretherketone (PEEK), can also be used to form at least part ofthe spacer implant. The electro-conductive strips are preferably used toline the inside of the cage in a vertical arrangement from top tobottom. The number of vertical strips is not critical and can range from1-100 or more but preferably a plurality of strips are employed on allsides of the spacer.

In another embodiment of the present invention, an implant is made byincorporating electro-conductive strips into an osteoconductivescaffolding material that is placed in the junction between the twobones that are to be fused. The strips are positioned to run from afirst bone surface to a second bone surface. In a preferred embodiment,β-tricalcium phosphate is used as an osteoconductive material that hasincorporated into it an electro-conductive material such as goldfilaments.

The external device worn by the patient produces a direct current in thestrips contained in the implant whereby bone growth is stimulated. Theexternal device can be any brace, belt, harness, corset, strap or bandthat surrounds the implant and can be worn by the patient. The externaldevice can contain magnets or electric coils with a power supply toprovide a current. The external device emits an electro-magnetic field,preferably variable, which according to Faraday's law will generate anelectric pulse in the center of the field thereby resulting in a directcurrent being imparted to the strips in the implant. The direct currentstimulates bone growth. In one embodiment the external emitter producesan electromagnetic field varying from 0.1 to 20 G to create anelectrical field at the fracture site of 1 to 100 mV/cm. Griffin, et al,Electrical Stimulation in Bone Healing: Critical Analysis by EvaluatingLevels of Evidence, ePlasty, Vol. 11, July 26, 2011, p. 303-353.

In another embodiment of the present invention, a spacer cage used foranterior lumbar interbody surgery or anterior cervical interbody surgeryaccording to the present invention is used to stimulate bone growth andpromote fusion. In a further embodiment the spacer cage containselectro-conductive materials (gold, zinc, titanium, etc) at the ends ofthe cage that generate small electric currents with micro-motion. Eachcompressive motion will generate a micro-current or piezioelectriccurrent to further promote fusion.

Referring to the drawings, FIG. 1A shows a perspective view of abiomechanical spacer 101 implant of the present invention containing ahollowed out interior 102 and two bone contact surfaces 103, 104. Bonecontact surface 103 abuts against a first bone surface (not shown) andbone surface 104 abuts against a second bone surface (not shown). FIG.1B shows a cutout view 105 of the interior 102 showingelectro-conductive strips 106 that run vertically from the first bonesurface (not shown) to the second bone surface (not shown). Implant 101is implanted in a mammal between two bone surfaces resulting from trauma(broken bone) and when the patient wears an external device (not shown)around the body adjacent to where the implant is located it produces anelectromagnetic field and a current is created in the electro-conductivestrips 106 thereby stimulating bone formation resulting in a fullyhealed union between the first bone surface 103 and second bone surface104.

FIG. 2 shows a cross sectional view of a bone fracture 201 that has aproximal bone section 202, a distal bone section 203 and an implant cageof the present invention 204. Cage 204 contains a plurality ofelectro-conductive strips 205 running from the proximal bone section 202to the distal section 203. The ends of electro-conductive strips 205come into close proximity to the distal end bone surface 206 andproximal end bone surface 207. When the patient wears an external device(not shown) around the body adjacent to where the implant is located thedevice produces an electromagnetic field and a current is created in theelectro-conductive strips 205 thereby stimulating bone formationresulting in a fully healed union between the distal bone section 203and the proximal bone section 202.

Another aspect of the present invention relates to a method of reducingspinal cord pain in a mammalian patient by implanting anelectro-conductive implant in a region in the patient directing electriccurrent in the implant whereby pain is reduced. In this regard theimplant acts as a spinal cord stimulator without the need for lead wiresor batteries. In this embodiment the implant contains strips of abiocompatible conductive metal or conductive polymer as described abovewith respect to the present implants used to promote bone fusion andbone growth. In this application for spinal cord stimulation the implantis made of a biocompatible substrate and the strips ofelectro-conductive material so as to fit the anatomy of the spine. Theimplant is positioned in a surgical procedure at a location adjacent towhere the spinal cord pain occurs. An external device is worn by thepatient wherein the device surrounds the area of the implant andproduces a magnetic field that creates a direct current in the implant.The direct current reduces pain similarly to a traditional spinal cordstimulator. The biocompatible electro-conductive metal is gold, nickelor titanium. The spinal cord stimulation according to the presentinvention is used for pain relief, nerve regeneration, and ischemic footor leg syndrome.

A bone growth inhibitor can optionally be added to the biocompatiblesubstrate in an implant used for spinal cord stimulation to preventunwanted bone growth in the region where the implant is located. Bonegrowth inhibitors include nerve growth factor (NGF) and PEEK.

In one embodiment of the present invention for use as a spinal cordstimulator, the implant comprises a calcium phosphate substrate,preferably β-tricalcium phosphate, and strips of gold, nickel ortitanium that are fixed or embedded into the calcium phosphatesubstrate. A preferred electro-conductive material is gold.

The following example illustrates the practice of the present inventionbut should not be construed as limiting its scope.

EXAMPLE 1 Femur Fusion

A human patient presents with a broken femur. A mechanical spacer/cageshown in FIGS. 1A and 1B is surgically implanted between the proximaland distal femur so that the cage abuts the distal femur and theproximal femur. The interior of the cage contains a plurality of goldstrips that run from the proximal femur to the distal femur and anosteoconductive scaffolding material such as autologous bone. Thepatient is given a leg band or wrap to wear around the femur adjacent towhere the implant is located. The leg band/wrap emits an electromagneticfield which produces a current in the gold strips resulting in boneformation and resulting in a fully healed union between the distal femurand the proximal femur.

Additional surgical procedures are performed using the implants of thepresent invention to repair non-union long bone fractures. Non-unionpodiatry fractures, non-union spinal fractures and skull fractures withcranioplasty.

The present invention can additionally be described as:

-   1. A method of reducing spinal cord pain in a mammalian patient in    need thereof which comprises:    -   a. implanting an electro-conductive implant in a region in the        patient where pain reduction is desired;    -   b. providing outside the patient's body a device that produces a        direct electric current in the implant whereby pain is reduced.-   2. The method of 1 above wherein the implant contains strips of a    biocompatible conductive metal or conductive polymer and the device    produces a magnetic field.-   3. The method of 2 above wherein the biocompatible conductive metal    is gold, nickel or titanium.-   4. The method of 4 above wherein the device produces a magnetic    field that produces an electric current in the gold, nickel or    titanium strips.-   5. A spinal cord stimulating implant which comprises:    -   a. a calcium phosphate substrate and    -   b. strips of gold, nickel or titanium fixed in the calcium        phosphate.-   6. In an implant for promoting bone growth at a bone fracture site    containing a first bone surface and a second bone surface, the    improvement which comprises:    -   a plurality of strips of an electro-conductive material        positioned in the implant from the first bone surface to the        second bone surface.-   7. The improved implant of 6 above wherein the electro-conductive    material is gold, nickel or titanium.-   8. In a method for promoting bone growth at a bone fracture site    containing a first bone surface and a second bone surface, the    improvement which comprises:    -   a. implanting an electro-conductive bone growth stimulating        implant in between the first bone surface and the second bone        surface wherein the implant contains a plurality of strips of an        electro-conductive material positioned in the implant from the        first bone surface to the second bone surface, and;    -   b. providing outside the patient's body, a device that produces        a direct current in the electro-conductive material whereby bone        growth is stimulated.-   9. The improved implant of 8 above wherein the electro-conductive    material is gold, nickel or titanium and the device emits a magnetic    field.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

All patents, published patent application, references and publicationscited above are incorporated herein by reference.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

All patents, published patent application, references and publicationscited above are incorporated herein by reference.

I claim:
 1. A method of stimulating bone growth for fusion promotion ina mammalian patient in need thereof which comprises: a. implanting anelectro-conductive bone growth stimulating implant in a region in thepatient where bone growth is desired; b. providing outside the patient'sbody a device that produces a direct current in the implant whereby bonegrowth is stimulated.
 2. The method of claim 1 wherein the implantcontains strips of a biocompatible conductive metal or conductivepolymer and the device produces a magnetic field and the device emits amagnetic field.
 3. The method of claim 2 wherein the biocompatibleconductive metal is gold, nickel or titanium.
 4. A method of stimulatingbone growth for fusion promotion in a mammalian patient which comprises:a. providing an electro-conductive biomechanical spacer/cage thatcontains a plurality of electro-conductive strips wherein saidconductive strips are configured in a spatial arrangement to promotebone growth in a desired direction; a. implanting said spacer/cage in aregion in the patient where bone growth is desired; b. providing outsidethe patient's body a device that produces an direct electric current inthe conductive strips whereby bone growth is stimulated.
 5. The methodof claim 4 wherein the implant contains strips of a biocompatibleconductive metal or conductive polymer and the device produces amagnetic field.
 6. The method of claim 5 wherein the biocompatibleconductive metal is gold, nickel or titanium.
 7. A bone growth kit whichcomprises: a. an electro-conductive bone growth stimulating implant andb. an external device that is capable of creating a direct electriccurrent in the implant wherein the device is worn by a mammalianpatient.
 8. The kit of claim 7 wherein implant contains strips of abiocompatible conductive metal or conductive polymer and the externaldevice emits a magnetic field.
 9. The kit of claim 8 wherein thebiocompatible conductive metal is gold, nickel or titanium.
 10. Anelectro conductive mammalian implant to induce fusion promotion of bonewhich comprises: a. a biocompatible substrate and b. anelectro-conducting material that produces a direct electric current whenstimulated from a source outside the mammal.
 11. The implant of claim 10wherein the substrate is an autograft, an allograft or a syntheticosteoconductive scaffold.
 12. The implant of claim 11 wherein theelectro-conductive material comprises strips of a biocompatibleconductive metal or conductive polymer and the direct electric currentis produced in said strips of conductive metal and conductive polymer bysubjecting them to a magnetic field.
 13. The implant of claim 12 whereinthe biocompatible conductive metal is gold, nickel or titanium.
 14. Anelectro conductive mammalian implant to induce fusion promotion of bonewhich comprises: a. an osteoconductive scaffolding, and b. strips ofbiocompatible electro-conductive material oriented in a linear directionof desired bone growth.
 15. The implant of claim 14 wherein thebiocompatible conductive metal is gold, nickel or titanium.
 16. Theimplant of claim 15 wherein the osteoconductive scaffolding is anautograft, an allograft or a synthetic osteoconductive scaffold.
 17. Amethod of stimulating bone growth for fusing a first bone surface to asecond bone surface in a mammalian patient in need thereof whichcomprises: a. implanting an electro-conductive bone growth stimulatingimplant between the first bone surface and the second bone surface; b.providing outside the patient's body a device that produces a directcurrent in the implant whereby bone growth is stimulated.
 18. The methodof claim 17 wherein the implant contains a plurality of strips of anelectro-conductive material positioned in the implant in substantially alinear fashion from the first bone surface to the second bone surfaceand the device emits a magnetic field.
 19. The method of claim 18wherein the electro-conductive material is gold, zinc or titanium.